Methane and the Paris Agreement temperature goals

Abstract

Meeting the Paris Agreement temperature goal necessitates limiting methane (CH 4 )-induced warming, in addition to achieving net-zero or (net-negative) carbon dioxide (CO 2 ) emissions. In our model, for the median 1.5°C scenario between 2020 and 2050, CH 4 mitigation lowers temperatures by 0.1°C; CO 2 increases it by 0.2°C. CO 2 emissions continue increasing global mean temperature until net-zero emissions are reached, with potential for lowering temperatures with net-negative emissions. By contrast, reducing CH 4 emissions starts to reverse CH 4 -induced warming within a few decades. These differences are hidden when framing climate mitigation using annual ‘CO 2 -equivalent’ emissions, including targets based on aggregated annual emission rates. We show how the different warming responses to CO 2 and CH 4 emissions can be accurately aggregated to estimate warming by using ‘warming-equivalent emissions', which provide a transparent and convenient method to inform policies and measures for mitigation, or demonstrate progress towards a temperature goal. The method presented (GWP*) uses well-established climate science concepts to relate GWP100 to temperature, as a simple proxy for a climate model. The use of warming-equivalent emissions for nationally determined contributions and long-term strategies would enhance the transparency of stocktakes of progress towards a long-term temperature goal, compared to the use of standard equivalence methods. This article is part of a discussion meeting issue ‘Rising methane: is warming feeding warming? (part 2)’.

Emissions Lock-in, Capacity, and Public Opinion: How Insights From Political Science Can Inform Climate Modeling Efforts

“…• CO 2 emissions (consumption) 2020). However, emissions of other GHGs significantly contribute to global warming, with methane accounting for about 40% of the contribution of GHGs to shortterm global warming (Cain et al, 2022;Höglund-Isaksson et al, 2020;IPCC, 2014;Saunois et al, 2020;Shindell et al, 2017). Mitigation will therefore require important changes also in the agricultural sector (Fesenfeld et al, 2018), raising different challenges and potential opposition from different interest groups, in particular in countries whose economies are more dependent on agriculture.…”

Technological avenues and market mechanisms to accelerate methane and nitrous oxide emissions reductions

“…Thus, if CH 4 levels were to suddenly fall to near-zero due to aggressive mitigation, its concentration would also decrease to zero in some decades, inducing a “global cooling” effect. 164 On the other hand, N 2 O has a longer lifetime, 109 years. As such, while an immediate reduction in emissions would reduce any additional increase in its atmospheric concentration, more than a century would still be required for its concentration to start decreasing.…”

Prioritize rapidly scalable methane reductions in efforts to mitigate climate change

“…These efforts are part of a broader trend that emphasizes emission reductions of short-lived climate forcers like CH 4 (Solomon et al 2010;Dreyfus et al 2022;Singh et al 2022). Reducing CH 4 emissions could bring benefits in the near-term when compared to reducing emissions of longer-lived climate forcers like CO 2 (Abernethy et al 2021;Cain et al 2022;Ming et al 2022;Abernethy and Jackson 2022). Besides rapid deployment, CH 4 reductions in the energy sector have the additional advantage of high short-term reductions in radiative forcing.…”